Preparation of cells from paraffin-embedded tissue for cytometry and cytomorphologic evaluation

A method is described for the preparation of monolayer smears from paraffin-embedded tissue. The smears are suitable for automated image analysis and DNA measurements while still allowing interpretation of nuclear morphology. The proposed technique uses enzyme treatment and syringing for cell dispersal. The preparation of cell monolayers is performed by cytocentrifugation. After staining the specimens with gallocyanin, nuclear DNA can be measured. Automated DNA measurements using the Leyden Television Analysis System (LEYTAS) showed coefficients of variation of 4.5% for the diploid cell population of suspended benign tissue. After DNA measurements, the specimens are counterstained using orange G and eosin. Since gallocyanin has spectral properties similar to those of hematoxylin, the obtained end product is comparable to specimens stained according to the routinely used Papanicolaou procedure. Using this technique, image cytometry can be applied to paraffin-embedded tissue in combination with conventional cytomorphologic study of the cells.